* {
  padding: 0;
  margin: 0;
}

body {
  background-image: linear-gradient(#fff, gray);
  height: 1000vh;
}

.rocket {
  position: fixed;
  right: 0;
  bottom: 0;
  width: 148px;
  height: 249px;
  background: url('./rocket.png') no-repeat;
  cursor: pointer;
  display: none;
}
/* 火箭动画 */
@keyframes rocketBg {
  0% {
    background-position-x: -148px;
  }
  100% {
    background-position-x: -892px;
  }
}

/* 鼠标移入 */
.rocket:hover {
  animation: rocketBg  1s steps(5) infinite alternate;
}